Once again, time to draw attention to a comment, this time from Benjamin Carlyle:
In short, I think that SOA is fine and a proven technology when it is possible to upgrade your whole architecture in one go to the new protocols. I think that REST is the only proven technology when only a tiny fraction of the overall architecture can be upgraded in a single sitting. You can’t upgrade the whole Web. REST accommodates this.
Be sure to read the full comment, which is longer than most of my blog entries.